US010219754B1
`
`( 12 ) United States Patent
`Lamego
`
`( 10 ) Patent No . : US 10 , 219 , 754 B1
`( 45 ) Date of Patent :
`Mar . 5 , 2019
`
`( 54 ) MODULATION AND DEMODULATION
`TECHNIQUES FOR A HEALTH
`MONITORING SYSTEM
`( 71 ) Applicant : Apple Inc . , Cupertino , CA ( US )
`( 72 ) Inventor : Marcelo M . Lamego , Cupertino , CA
`( US )
`( 73 ) Assignee : Apple Inc . , Cupertino , CA ( US )
`Subject to any disclaimer , the term of this
`( * ) Notice :
`patent is extended or adjusted under 35
`U . S . C . 154 ( b ) by 0 days .
`( 21 ) Appl . No . : 14 / 621 , 268
`( 22 )
`Filed :
`Feb . 12 , 2015
`Related U . S . Application Data
`( 60 ) Provisional application No . 62 / 047 , 818 , filed on Sep .
`9 , 2014 .
`( 51 ) Int . CI .
`A61B 5 / 00
`( 2006 . 01 )
`( 52 ) U . S . CI .
`CPC . . . . . . . . . . A61B 5 / 7228 ( 2013 . 01 ) ; A61B 5 / 0059
`( 2013 . 01 ) ; A61B 5 / 681 ( 2013 . 01 ) ; A61B
`5 / 7203 ( 2013 . 01 ) ; A61B 5 / 725 ( 2013 . 01 ) ;
`A61B 5 / 7225 ( 2013 . 01 ) ; A61B 5 / 7278
`( 2013 . 01 )
`
`( 56 )
`
`( 58 ) Field of Classification Search
`CPC
`. . . . . . . . . . . . . . . . A61B 5 / 0059 ; A61B 5 / 0084
`See application file for complete search history .
`References Cited
`U . S . PATENT DOCUMENTS
`5 , 349 , 952 A *
`9 / 1994 McCarthy . . . . . . . . . . . A61B 5 / 0059
`356 / 41
`2012 / 0253155 Al * 10 / 2012 Diab . . . . . . . . . . A61B 5 / 14551
`600 / 324
`* cited by examiner
`Primary Examiner — Hien Nguyen
`( 74 ) Attorney , Agent , or Firm — Brownstein Hyatt Farber
`Schreck , LLP
`( 57 )
`ABSTRACT
`An electronic device includes one or more light sources for
`emitting light toward a body part of a user and one or more
`optical sensors for capturing light samples while each light
`source is turned on and for capturing dark samples while the
`light source ( s ) are turned off . A signal produced by the one
`or more optical sensors is demodulated produce multiple
`demodulated signals . Each demodulated signal is received
`by one or more decimation stages to produce a signal
`associated with each light source . Each signal associated
`with the light source ( s ) is analyzed to estimate or determine
`a physiological parameter of the user .
`6 Claims , 9 Drawing Sheets
`
`TURN ON LIGHT
`SOURCE TO ILLUMINATE
`USER ' S SKIN
`
`400
`
`OPTICAL SENSOR SENSES 1402
`AN AMOUNT OF LIGHT
`
`400
`TURN OFF | YES
`LIGHT
`SOURCE
`
`ANOTHER
`LIGHT
`SOURCE ?
`
`404
`
`NO
`T - 408
`DIGITIZED SIGNAL
`RECEIVED FROM OPTICAL
`SENSOR
`
`DEMODULATE DIGITIZED
`SIGNAL
`
`410
`
`LOW PASS FILTER AND T - 412
`DECIMATION CIRCUIT
`RECEIVE AND PROCESS
`DEMODULATED SIGNALS
`
`ANALYZE SIGNALS TO
`DETERMINE
`PHYSIOLOGICAL
`PARAMETER
`
`414
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`atent
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`Mar . 5 , 2019
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`Sheet 1 of 9
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`US 10 , 219 , 754 B1
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`100
`
`102
`106
`
`toll
`
`108
`
`104
`
`FIG . 1
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`Sheet 2 of 9
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`US 10 , 219 , 754 B1
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`102
`
`202
`
`204
`
`200
`
`FIG . 2
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`U . S . Patent ve savo sum
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`atent
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`Mar . 5 , 2019
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`Sheet 3 of 9
`
`u s 120
`
`US 10 , 219 , 754 B1
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`312
`
`HEALTH MONITORING SYSTEM
`
`306
`
`SENSOR
`
`NETWORK / COMM .
`
`310
`
`PROCESSING DEVICE
`
`LIGHT SOURCES
`
`OPTICAL SENSOR
`
`316 +
`
`202 +
`
`104
`
`300
`
`204
`
`DISPLAY
`
`PROCESSING DEVICE
`
`308
`
`POWER SOURCE
`
`314
`
`304
`
`I / O DEVICE
`
`MEMORY
`
`302
`
`FIG . 3
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`Sheet 4 of 9
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`US 10 , 219 , 754 B1
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`TURN ON LIGHT
`1400
`SOURCE TO ILLUMINATE
`USER ' S SKIN
`
`OPTICAL SENSOR SENSES
`AN AMOUNT OF LIGHT
`
`T - 402
`
`- 406
`TURN OFF | YES
`LIGHT
`SOURCE
`
`ANOTHER
`LIGHT
`SOURCE ?
`
`404
`
`NO
`DIGITIZED SIGNAL
`RECEIVED FROM OPTICAL
`SENSOR
`
`- 408
`
`DEMODULATE DIGITIZED |
`SIGNAL
`
`410
`
`412
`
`- 414
`
`LOW PASS FILTER AND
`DECIMATION CIRCUIT
`RECEIVE AND PROCESS
`DEMODULATED SIGNALS
`
`ANALYZE SIGNALS TO
`DETERMINE
`PHYSIOLOGICAL
`PARAMETER
`FIG . 4
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`Sheet 5 of 9
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`US 10 , 219 , 754 B1
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`508
`
`514
`
`520
`
`INTENSITY
`
`X = OPTICAL SENSOR
`CAPTURES SAMPLE
`
`500
`
`504 506
`
`sio 512 516 518
`524
`FIG . 5
`
`TIME
`TIIVIL
`
`522
`
`508
`
`514
`
`2121212149
`
`INTENSITY YVVVV
`
`X = OPTICAL SENSOR
`CAPTURES SAMPLE
`
`TIME
`
`602
`FIG . 6
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`Sheet 6 of 9
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`US 10 , 219 , 754 B1
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`718
`
`716
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`714
`
`710
`
`702
`
`704
`
`1708
`DEMODULATION
`OPERATIONS
`
`720
`
`DEMULTIPLIXER AND MULTIPLIER CIRCUIT
`DECIMATION
`LOW PASS FILTER
`
`.
`
`? .
`
`DECIMATION
`LOW PASS FILTER
`LADH
`
`X
`
`700
`
`FIG . 7
`
`STAGE K
`
`STAGE 1
`
`706
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`Sheet 7 of 9
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`US 10 , 219 , 754 B1
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`DETERMINE THE MATRIX
`VALUES
`
`800
`
`VERIFY THE MATRIX
`VALUES
`
`- 802
`
`NO VERIFIED ? »
`
`. 804
`
`APPLY THE MATRIX
`
`806
`
`NO RECALCULATE
`MATRIX ?
`
`808
`
`YES
`
`FIG . 8
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`Sheet 8 of 9
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`US 10 , 219 , 754 B1
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`TURN ON A SINGLE LIGHT 1900
`SOURCE FOR A GIVEN
`TIME PERIOD
`
`PROCESS SIGNAL
`T902
`PRODUCED BY OPTICAL
`SENSOR TO DETERMINE
`MATRIX VALUES
`
`906
`
`TURN OFF
`LIGHT
`SOURCE
`
`904
`
`ALL LIGHT
`SOURCES ?
`
`FIG . 9
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`U . S . Patent
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`atent
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`Mar . 5 , 2019
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`Sheet 9 of 9
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`US 10 , 219 , 754 B1
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`TURN ON ALL LIGHT
`SOURCES EXCEPT ONE
`LIGHT SOURCE FOR A
`GIVEN TIME PERIOD
`
`PROCESS SIGNAL
`PRODUCED BY OPTICAL
`SENSOR
`
`1000
`
`1002
`
`- 1004
`
`ZERO
`OUTPUT ?
`
`NO
`
`- 1008
`YES
`
`ALL LIGHT
`SOURCES ?
`
`NO
`
`- 1010
`
`TURN OFF
`LIGHT
`SOURCES
`
`RECALCULATE MATRIX I
`VALUES
`
`1006
`
`FIG . 10
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`US 10 , 219 , 754 B1
`
`MODULATION AND DEMODULATION
`TECHNIQUES FOR A HEALTH
`MONITORING SYSTEM
`
`20
`
`nents in the electronic device . Each signal associated with
`the light source ( s ) is analyzed to estimate or determine a
`physiological parameter of the user .
`In another aspect , a method for processing the signal
`5 received from the light sensor can include capturing multiple
`CROSS - REFERENCE TO RELATED
`light samples while each light source emits light toward the
`APPLICATION
`body part of the user and converting the multiple light
`samples into the signal . The light sources can be modulated
`This application claims the benefit under 35 U . S . C . §
`( e . g . , turned on and off ) according to a particular modulation
`119 ( e ) of U . S . Provisional Patent Application No . 62 / 047 ,
`pattern . The signal produced by the optical sensor is then
`818 . filed Sep . 9 , 2014 , entitled “ Modulation and Demodu - 10 demodulated to produce multiple demodulated signals . Each
`lation Techniques for a Health Monitoring System , ” the
`demodulated signal is associated with a particular light
`entirety of which is incorporated herein by reference .
`source . Each demodulated signal is then be processed by at
`least one decimation stage . In one embodiment , each deci
`TECHNICAL FIELD
`mation stage includes a low pass filter that receives a
`15 demodulated signal and a decimation circuit operably con
`The present invention relates generally to health moni -
`nected to an output of the low pass filter . A demultiplexer
`and multiplier circuit may then process the signals . Each
`toring systems , and more particularly to modulation and
`demodulation techniques for a health monitoring system that
`signal associated with the light source ( s ) is analyzed to
`estimate or determine a physiological parameter of the user .
`includes one or more optical sensors .
`In yet another aspect , a method for operating an electronic
`BACKGROUND
`device that includes multiple light sources , an optical sensor ,
`and a processing device operably connected to the optical
`Health monitoring devices , such as fitness and wellness
`sensor can include turning on each light source one at a time
`and emitting light toward a body part of a user and capturing
`devices , are capable of measuring a variety of physiological
`parameters and waveforms non - invasively via optical sens - 25 multiple light samples while each light source emits light
`ing . Light is applied to a measurement site , such as a user ' s
`toward the body part of the user and converting the multiple
`wrist , finger , and ear , and the light is absorbed and scattered
`light samples into a signal . The signal is converted into a
`throughout the skin . An optical sensor in the health moni
`digital signal , and the digital signal is demodulated to
`toring device captures the light that is reflected from or
`produce multiple demodulated signals . Each demodulated
`transmitted through the skin . The optical sensor , however , is 30 signal is then processed by at least one decimation stage . In
`subject to interferences caused by fluorescent bulbs , sun
`one embodiment , each decimation stage includes a low pass
`light , the electricity grid or network , and motion artifacts
`filter that receives a demodulated signal and a decimation
`that are caused by the relative motion between the optical
`circuit operably connected to an output of the low pass filter .
`sensor and the user ' s measurement site . Thus , the light
`Each signal associated with the light source ( s ) is analyzed to
`collected by the light sensor contains a component from the 35 estimate or determine a physiological parameter of the user .
`measurement site and component from one or more inter
`ferences . To estimate the physiological parameter and wave
`BRIEF DESCRIPTION OF THE DRAWINGS
`form , the optical sensor coverts the collected light into
`Embodiments of the invention are better understood with
`electrical signals , and the signal that represents the interfer
`ence component is typically subtracted from the signal 40 reference to the following drawings . The elements of the
`representing the measurement site component . After sub -
`drawings are not necessarily to scale relative to each other .
`traction , only the component from the measurement site
`Identical reference numerals have been used , where pos
`should remain , which is the component that is used to
`sible , to designate identical features that are common to the
`estimate the physiological parameter . However , subtraction
`figures .
`cannot be performed instantaneously . A time delay exists 45
`FIG . 1 a perspective front view of one example of an
`between sampling the light and subtracting the interference
`electronic device that provides health - related information ;
`component . The time delay can result in the creation of
`FIG . 2 depicts a back view of the electronic device 100
`aliases in the signal , and the aliases produce errors in the
`estimation of the physiological parameter .
`SUMMARY
`In one aspect , an electronic device includes one or more
`light sources for emitting light toward a body part of a user
`and one or more optical sensors for capturing light samples 55
`while each light source is turned on and for capturing dark
`samples while the light source ( s ) are turned off . A signal
`produced by the one or more optical sensors is demodulated
`produce multiple demodulated signals . Each demodulated
`signal is received by one or more decimation stages to
`produce a signal associated with each light source . A demul -
`tiplexer and multiplier circuit operably can be connected to
`an output of the decimation stage . The demultiplexer sepa
`rates the signals by each associated light source and the
`multiplier multiplies each signal by one or more respective 65
`weights . The weights adjust the signals for variations in
`temperature and operating parameters of various compo -
`
`FIG . 3 is an illustrative block diagram of the electronic
`50 device 100 shown in FIGS . 1 and 2 ;
`FIG . 4 is a flowchart of one example method of operating
`the health monitoring system 312 in FIG . 3 ;
`FIGS . 5 - 6 depict example modulation patterns suitable for
`use in blocks 400 and 402 in FIG . 4 ;
`FIG . 7 is a data flow diagram of a processing channel that
`performs blocks 408 , 410 , and 412 in FIG . 4 ;
`FIG . 8 is a flowchart of one example method of deter
`mining a matrix used in block 718 of FIG . 7 ;
`FIG . 9 is a flowchart of one example method of perform
`60 ing block 800 in FIG . 8 ; and
`FIG . 10 is a flowchart of one example method of per
`forming block 802 in FIG . 8 .
`DETAILED DESCRIPTION
`Embodiments described herein provide modulation and
`demodulation techniques that reduce or eliminate undesired
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`US 10 , 219 , 754 B1
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`interferences and produce demodulated signals that can be
`analyzed to estimate a physiological parameter of a user . A
`time multiplexed modulation pattern is used to turn the light
`sources on and off and to cause the optical sensor to capture
`multiple light and dark samples . Demodulation operations 5
`are applied to the signal produced by the optical sensor to
`produce a signal associated with each light source . In
`general , the demodulation operation can be
`
`the electronic device 100 is implemented as a wearable
`communication device . Other embodiments can implement
`the electronic device differently . As described earlier , the
`electronic device can be a smart telephone , a gaming device ,
`a digital music player , a device that provides time , a health
`assistant , and other types of electronic devices that provide
`health - related information .
`The electronic device 100 includes an enclosure 102 at
`least partially surrounding a display 104 and one or more
`10 buttons 106 or input devices . The enclosure 102 can form an
`outer surface or partial outer surface and protective case for
`sin2 . 7 for cos 27
`the internal components of the electronic device 100 , and
`may at least partially surround the display 104 . The enclo
`sure 102 can be formed of one or more components operably
`The demodulated signals may then be processed by one or 15 connected together , such as a front piece and a back piece .
`Alternatively , the enclosure 102 can be formed of a single
`more decimation stages . Each decimation stage can include
`a low pass filter and a decimation circuit .
`piece operably connected to the display 104 .
`Any suitable type of electronic device can include a health
`The display 104 can be implemented with any suitable
`monitoring system . Example electronic devices include , but
`technology , including , but not limited to , a multi - touch
`are not limited to , a smart telephone , a headset , a pulse 20 sensing touchscreen that uses liquid crystal display ( LCD )
`oximeter , a digital media player , a tablet computing device ,
`technology , light emitting diode ( LED ) technology , organic
`and a wearable electronic device . A wearable electronic
`light - emitting display ( OLED ) technology , organic elec
`device can include any type of electronic device that can be
`troluminescence ( OEL ) technology , or another type of dis
`worn on a limb of a user . The wearable electronic device can
`play technology . A button 106 can take the form of a home
`be affixed to a limb or body part of a user , such as a wrist , 25 button , which may be a mechanical button , a soft button
`an arm , a finger , a leg , an ear , or a chest . In some embodi -
`( e . g . , a button that does not physically move but still accepts
`ments , the wearable electronic device is worn on a limb of
`inputs ) , an icon or image on a display or on an input region ,
`a user with a band that attaches to the body and includes a
`and so on . Other buttons or mechanisms can be used as
`holder or case to detachably or removably hold the elec -
`input / output devices , such as a speaker , a microphone , an
`tronic device , such as an armband , an ankle bracelet , a leg 30 on / off button , a mute button , or a sleep button . In some
`band , and / or a wristband . In other embodiments , the wear -
`embodiments , the button or buttons 106 can be integrated as
`able electronic device is permanently affixed or attached to
`part of a cover glass of the electronic device .
`The electronic device 100 can be permanently or remov
`a band , and the band attaches to the body of the user .
`As one example , a wearable electronic device can be
`ably attached to a band 108 . The band 108 can be made of
`implemented as a wearable health assistant that provides 35 any suitable material , including , but not limited to , leather ,
`health - related information ( whether real - time or not ) to the
`metal , rubber or silicon , fabric , and ceramic . In the illus
`user , authorized third parties , and / or an associated monitor -
`trated embodiment , the band is a wristband that wraps
`ing device . The wearable health assistant may be configured
`around the user ' s wrist . The wristband can include an
`to provide health - related information or data such as , but not
`attachment mechanism ( not shown ) , such as a bracelet clasp ,
`limited to , heart rate data , blood pressure data , temperature 40 Velcro , and magnetic connectors . In other embodiments , the
`data , blood oxygen saturation level data , diet / nutrition infor -
`band can be elastic or stretchy such that it fits over the hand
`mation , medical reminders , health - related tips or informa -
`of the user and does not include an attachment mechanism .
`tion , or other health - related data . The associated monitoring
`FIG . 2 depicts a back view of the electronic device 100
`device may be , for example , a tablet computing device ,
`shown in FIG . 1 . As described earlier , the electronic device
`phone , personal digital assistant , computer , and so on .
`45 can include one or more sensors , and at least one of these
`As another example , the electronic device can be config -
`sensors may provide health - related information . As one
`ured in the form of a wearable communications device . The
`example , the wearable communication device can include an
`wearable communications device may include a processor
`optical sensor , such as a photoplethysmography ( PPG ) sen
`coupled with or in communication with a memory , one or
`sor . A PPG sensor uses light to measure changes in the
`more sensors , one or more communication interfaces , output 50 volume of a part of a user ' s body . As the light passes through
`devices such as displays and speakers , one or more input
`the user ' s skin and into the underlying tissue , some light is
`devices , and a health monitoring system . The communica -
`reflected , some is scattered , and some light is absorbed ,
`tion interface ( s ) can provide electronic communications
`depending on what the light encounters . Blood can absorb
`between the communications device and any external com -
`light more than surrounding tissue , so less reflected light will
`munication network , device or platform , such as but not 55 be sensed by the PPG sensor when more blood is present .
`limited to wireless interfaces , Bluetooth interfaces , USB
`The user ' s blood volume increases and decreases with each
`interfaces , Wi - Fi interfaces , TCP / IP interfaces , network
`heartbeat . A PPG sensor detects changes in blood volume
`communications interfaces , or any conventional communi -
`based on the reflected light , and one or more physiological
`cation interfaces . The wearable communications device may
`parameters of the user can be determined by analyzing the
`provide information regarding time , health , statuses or exter - 60 reflected light . Example physiological parameters include ,
`nally connected or communicating devices and / or software
`but are not limited to , heart rate and respiration .
`executing on such devices , messages , video , operating com -
`The electronic device 100 includes one or more apertures
`mands , and so forth ( and may receive any of the foregoing
`200 in the enclosure 102 . Each aperture is associated with a
`from an external device ) , in addition to communications .
`light source 202 . In one embodiment , each light source is
`Referring now to FIG . 1 , there is shown a perspective 65 implemented as a light - emitting diode ( LED ) . Four aper
`view of one example of an electronic device that provides
`tures 200 and four light sources 202 are used in the illus
`health - related information . In the illustrated embodiment ,
`trated embodiment . Other embodiments can include any
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`US 10 , 219 , 754 B1
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`The one or more I / O devices 304 can transmit and / or
`number of light sources 200 . For example , two light sources
`receive data to and from a user or another electronic device .
`can be used in some embodiments .
`One example of an I / O device is button 106 in FIG . 1 . The
`The light sources 202 can operate at the same light
`1 / 0 device ( s ) 304 can include a display , a touch sensing
`wavelength range , or the light sources can operate at differ -
`ent light wavelength ranges . As one example , with two light 5 input surface such as a track pad , one or more buttons , one
`sources one light source may transmit light in the visible
`or more microphones or speakers , one or more ports such as
`a microphone port , and / or a keyboard .
`wavelength range while the other light source can emit light
`The electronic device 100 may also include one or more
`in the infrared wavelength range . With four light sources ,
`sensors 306 positioned substantially anywhere on the elec
`two light sources may transmit light in the visible wave
`length range while the other two light sources can emit light 10 tronic device 100 . The sensor or sensors 306 may be
`configured to sense substantially any type of characteristic ,
`in the infrared wavelength range . For example , in one
`such as but not limited to , images , pressure , light , touch ,
`embodiment , at least one light source can emit light in the
`heat , position , motion , and so on . For example , the sensor ( s )
`wavelength range associated with the color green while
`308 may be an image sensor , a heat sensor , a light or optical
`another light source transmits light in the infrared wave - 15 sensor , a pressure transducer , a magnet , a gyroscope , an
`length range . When a physiological parameter of the user
`accelerometer , and so on .
`will be determined , the light sources emit light toward the
`The power source 308 can be implemented with any
`device capable of providing energy to the electronic device
`user ' s skin and the optical sensor 204 senses an amount of
`reflected light . The optical sensor 204 may sense the
`100 . For example , the power source 308 can be one or more
`reflected light through an aperture ( not shown ) that is 20 batteries or rechargeable batteries , or a connection cable that
`formed in the electronic device . As will be described in more
`connects the remote control device to another power source
`detail later , a modulation pattern can be used to turn the light
`such as a wall outlet .
`sources on and off and sample or sense the reflected light .
`The network communication interface 310 can facilitate
`FIG . 3 is an illustrative block diagram of the electronic
`transmission of data to or from other electronic devices . For
`device 100 shown in FIG . 1 . The electronic device 100 can 25 example , a network communication interface can transmit
`include the display 104 , one or more processing devices 300 ,
`electronic signals via a wireless and / or wired network con
`memory 302 , one or more input / output ( 1 / 0 ) devices 304 ,
`nection . Examples of wireless and wired network connec
`one or more sensors 306 , a power source 308 , a network
`tions include , but are not limited to , cellular , Wi - Fi , Blu
`communications interface 310 , and a health monitoring
`etooth , IR , and Ethernet .
`system 312 . The display 104 may provide an image or video 30
`The health monitoring system 312 can include the light
`output for the electronic device 100 . The display may also
`sources 202 , one or more optical sensors 204 , and a pro
`provide an input surface for one or more input devices , such
`cessing device 316 . The processing device 316 may be any
`as , for example , a touch sensing device and / or a fingerprint
`suitable type of processing device . In one embodiment , the
`sensor . The display 104 may be substantially any size and
`processing device 316 is a digital signal processor . The
`may be positioned substantially anywhere on the electronic 35 processing device 316 may receive signals from the optical
`sensor ( s ) 204 and processes the signals to correlate the
`device 100 .
`The processing device 300 can control some or all of the
`signal values with a physiological parameter of the user . As
`operations of the electronic device 100 . The processing
`one example , the processing device can apply one or more
`device 300 can communicate , either directly or indirectly
`demodulation operations to the signals received from the
`with substantially all of the components of the electronic 40 optical sensor . Additionally , the processing device may
`device 100 . For example , a system bus or signal line 314 or
`control the modulation ( e . g . , turning on and off ) of the light
`other communication mechanisms can provide communica -
`sources 202 according to a given modulation pattern . In one
`tion between the processing device ( s ) 300 , the memory 302 ,
`embodiment , one or more modulation patterns may be
`the I / O device ( s ) 304 , the sensor ( s ) 306 , the power source
`stored in memory 302 and accessed by the processing device
`308 , the network communications interface 310 , and / or the 45 316 to modulate the light sources 202 .
`health monitoring system 312 . The one or more processing
`As discussed earlier , the light sources can emit light in the
`devices 300 can be implemented as any electronic device
`visible and / or infrared wavelength ranges . The optical sen
`capable of processing , receiving , or transmitting data or
`sor or sensors 204 is implemented as a photodetector that
`instructions . For example , the processing device ( s ) 200 can
`senses light and converts the light into an electrical signal
`each be a microprocessor , a central processing unit ( CPU ) , 50 that represents the amount of light sensed by the photode
`an application - specific integrated circuit ( ASIC ) , a digital
`tector . In one embodiment , the photodetector can be a
`signal processor ( DSP ) , or combinations of such devices . As
`photodiode . Other embodiments can use a different type of
`described herein , the term “ processing device ” is meant to
`photodetector , such as a phototube or photoresistor .
`encompass a single processor or processing unit , multiple
`In another embodiment , the processing device 316 is not
`processors , multiple processing units , or other suitably con - 55 included in the health monitoring system 312 and the
`figured computing element or elements .
`processing device 300 receives signals from the optical
`The memory 302 can store electronic data that can be used
`sensor ( s ) 204 and processes the signals to correlate the
`by the electronic device 100 . For example , a memory can
`signal values with a physiological parameter of the user .
`store electrical data or content such as , for example , audio
`Additionally or alternatively , the processing device 300 can
`and video files , documents and applications , device settings 60 control the operations of the light sources ( e . g . , turn on and
`and user preferences , timing and control signals or data for
`off ) . One or more modulation patterns may be stored in
`the health monitoring system 312 , data structures or data
`memory 302 and accessed by the processing device 300 to
`bases , and so on . The memory 302 can be configured as any
`modulate the light sources 202 .
`type of memory . By way of example only , the memory can
`I
`t should be noted that FIGS . 1 - 3 are illustrative only . In
`be implemented as random access memory , read - only 65 other examples , an electronic device may include fewer or
`memory , Flash memory , removable memory , or other types
`more components than those shown in FIG . 3 . Additionally
`or alternatively , the electronic device can be included in a
`of storage elements , or combinations of such devices .
`
`-13-
`
`MASIMO 2025
`Apple v. Masimo
`IPR2022-01291
`
`

`

`US 10 , 219 , 754 B1
`
`lation cycle frequencies may range , as a non - limiting
`system and one or more components shown in FIG . 3 are
`example , from one hundred hertz to several hundred kilo
`separate from the electronic device but in communication
`hertz .
`with the electronic device . For example , an electronic device
`In many examples , the modulation cycle frequency and
`may be operatively connected to , or in communication with
`a separate display . As another example , one or more appli - 5 the sampling frequency may be interrelated . For example ,
`cations or data can be stored in a memory separate from the
`certain embodiments may be limited by hardware or soft
`ware to a particular maximum sampling frequency . In such
`electronic device . As another example , a processing device
`an example , the modulation cycle frequency may be selected
`in communication with the electronic device can control
`such that the transmitted signal can be adequately recon
`various functions in the electronic device and / or process ;
`10 structed . In some cases , the modulation cycle may be less
`data received from the electronic device . In some embodi
`than half the sampling rate . Stated another way , if a certain
`ments , the separate memory and / or processing device can be
`embodiment requires a particular bandwidth , the sampling
`in a cloud - based system or in an associated monitoring
`frequency may be at least twice the selected maximum
`device .
`frequency of the selected bandwidth .
`Referring now to FIG . 4 , there is shown a flowchart of one 15
`Other embodiments can obtain a different number of
`1a nowchart of one 15
`example method of operating the health monitoring system
`samples and / or operate at a different frequency . The fre
`312 in FIG . 3 . Initially , a light source is turned on to
`quency may be determined based on a number of factors ,
`illuminate the user ' s skin and the optical sensor senses an
`one of which is the harmonics of the electrical network or
`grid . For example , when an electrical network produces a
`amount of reflected or transmitted light ( blocks 400 , 402 ) . A
`determination can then be made at block 404 as to whether 20 signal at 60 Hz , the harmonics are multiples of 60 ( e . g . , 120
`or not another light source is to be turned on . For example ,
`Hz , 180 Hz , 240 Hz , etc . ) . Also , some electrical networks
`in one embodiment , the light sources are turned on sequen
`produce a signal at 50 Hz , and the harmonics of multiples of
`tially and the optical sensor senses the light multiple times
`50 Hz ( e . g . , 100 Hz , 150 Hz , 200 Hz , etc . ) .
`Additionally , some electrical networks can be less reliable
`while each light source is turned on .
`If another light source is to be turned on , the process 25 at generating a signal with a specific frequency , and the
`passes to block 406 where the light source that is currently
`frequency may vary by a certain amount or deviation ( e . g . ,
`turned on is turned off . The method then returns to block 400
`a frequency of 60 Hz may operate at 60 + / - 1 % Hz ) . And the
`deviation increases with each harmonic . Thus ,
`in one
`and repeats until all of the light sources have been turned on
`embodiment , the frequency of the modulation cycle is
`and the optical sensor has obtained light samples .
`1 of the 30 selected to be in a harmonic gap that exists between the
`When a determination is made at block 404 that all of the 30
`various harmonics and harmonic deviations of at least one
`light sources have been turned on , the process continues at
`electrical network .
`block 408 where the signal received from the optical sensor
`The illustrated modulation patterns are time - multiplexed
`is digitized by inputting the signal into an analog - to - digital
`modulation patterns that drive the light sources . The time
`converter . The digitized signal is then demodulated at block 35 periods when the light sources are turned on and off are
`410 . Demodulating the signal produces multiple demodu
`multiplexed in time . In FIG . 5 , the first light source is turned
`lated signals , with a demodulated signal associated with
`on for the time period 500 . The other three light sources are
`each light source . Each demodulated sign